激光制造正前角金刚石磨具与正前角磨削机理研究

Hard and brittle materials (such as engineering ceramics, hard alloys, etc.) are widely used in aerospace, new energy, automotive, general machinery manufacturing and other fields. And the processing of these materials is mainly realized through super hard abrasive tools (such as diamond grinding wheels) grinding currently. However, surface/subsurface damages such as micro cracks, residual stress, phase transformation, dislocations and corrugations will occur on the processed hard brittle material accompany with the hard abrasive tool grinding. In order to solve this problem, a novel method that using super hard abrasive tools with positive rake angle for hard and brittle materials grinding has been put forward for the first time. Ultrashort pulsed laser will be used for diamond abrasive grains ablation to make the apex angle of the grains form over 90 degrees to less than 90 degrees. Thus, the traditional negative rake angle grinding of super hard abrasive will be changed to positive rake angle grinding subsequently. The material removal mechanism during ultrashort pulsed laser ablating diamond abrasive grains as well as the surface/subsurface damage mechanism of positive rake angle grinding on hard and brittle materials will be researched through molecular dynamics simulation and experiment methods. The interaction mechanism between ultrashort pulsed laser and diamond abrasive grains will be expounded and the systematic theory of super hard abrasive tools positive rake angle grinding on hard and brittle materials will be hence established and novel super hard abrasive tools with positive rake angle will also be invented. The objective of improving the surface/subsurface integrity of hard and brittle materials will be achieved eventually. The technology of positive rake angle grinding on hard and brittle material is significant for the improvement and consummation of the grinding theory and can be extended to the grinding process of other materials.

硬脆材料（如工程陶瓷、硬质合金等）在航空航天、新能源、汽车、通用机械制造等领域应用广泛。目前，硬脆材料的加工主要通过超硬磨料磨具（如金刚石砂轮）磨削实现。针对超硬磨料磨具磨削硬脆材料时易产生微裂纹、残余应力、相变、位错、波纹等表面/亚表面损伤的问题，首次提出超硬磨料正前角磨削硬脆材料新构想。采用超短脉冲激光烧蚀金刚石磨粒，使磨粒顶角由大于90°变为小于90°，从而将传统的超硬磨料负前角磨削方式变为正前角磨削。通过分子动力学建模模拟并与试验相结合，研究超短脉冲激光烧蚀金刚石磨粒的去除机制，研究正前角磨削硬脆材料表面/亚表面损伤机理，阐明超短脉冲激光与金刚石磨粒相互作用的机理，建立超硬磨料正前角磨削硬脆材料的系统理论，发明一种具有正前角的新型超硬磨料磨具。最终达到提高硬脆材料加工表面/亚表面完整性的目标。正前角磨削硬脆材料技术对于完善磨削加工理论具有重要意义，还可推广到其它材料的磨削加工领域。

本项目首次提出了正前角金刚石磨料磨削硬脆材料的新构想，改变传统的基于“滑擦—耕犁—切削”过程的磨削加工模式，发明了一种磨粒规则排布的新型正前角超硬磨料磨具。通过理论研究和仿真分析，揭示了超短脉冲激光与金刚石材料相互作用的机理及超短脉冲激光烧蚀加工金刚石磨粒成正前角的去除机制，研究了不同激光加工参数对金刚石材料表面形貌、表面质量的影响。采用优化的工艺参数成功制造出具有正前角的单颗金刚石磨粒和正前角金刚石端面磨削工具。基于分子动力学方法和单颗正前角磨粒磨削探索了正前角磨削硬脆材料的机理。开展了正、负前角端面砂轮的磨削对试验，对比研究了不同工艺参数下具有正前角和负前角的聚晶金刚石端面砂轮磨削硬质合金过程中磨削力、磨削加工表面形貌和表面粗糙度的变化规律，论证了正前角磨削的可行性和优势，提高了难加工材料加工表面完整性。